Pneumatic motor



June 22, 1965 w. JAKOWCHUK 3,190,132

PNEUMATIC MOTOR Filed Feb. 4,; 196 3 5 Sheets-Sheet l Rik June 22, 1965 w. JAKOWCHUK PNEUMATIC MOTOR 5 Sheets-Sheet 2 Filed Feb. 4,

a l. I I l l I i I I .l I l v V Ill-Ill .lllrllllllllllll I I HHhH IH I I I HI I L l I I I 4 l I I l l l I I ms g June 22, 1965 w. JAKOWCHUK PNEUMATIC MOTOR 5 Sheets-Sheet 3 Filed Feb. 4, 1963 June 22, 1965 w. JAKOWCHUK PNEUMATIC MOTOR 5 Sheets-Sheet 4 Filed Feb. 4, 1963 F c? I jzvegzim" J/QZZe/"JMUMCM Maia/1,74% y/I/ZUW L \mw a 8W3 mm 9% fi m E & m W m mkww United States Patent Office v 3,190,182- Patented June 22, 1965 3,190,182 PNEUMATIC MOTOR Waltei-Jakowchuk, Melrose Park, II!., assignor to. Mead Specialties Company, Inc., Chicago, 111. Filed Feb. 4, 1963, Ser. No. 255,970 8 Claims. (Cl. 91- -2).

This invention relates to a pneumatic motor, and, more particularly, to a pneumatic motor employed as, part of a pneumatic timing device. i

This invention has utility in connection with the type of timer seen in Mead Patent No. 2,946,346. There, a

by a sequence of events is adapted to be carefully regulated in a given time. 1

Still another object of the invention is to provide a novel pneumatic timer adapted for one revolution operation whereby a series of events canbe timed according to one revolution of a control shaft, the shaft rotating slowly and only through one revolution until intentionally reactuated.

A further object of the invention is to provide a novel interlock bleed valve which finds utility, for example, in conjunction with the one-revolution operation just referred to. r

Other objects and advantages of the invention may be seen in the details of construction and operation set down in this specification.

The invention is explained in conjunction withan illustrative embodiment in the accompanying drawings, in which FIG. 1 is a fragmentarytop plan view of a pneumatic timer constructed according to the inventive teachtugs;

FIG. 2 is a fragmentary front elevational view of the apparatus of FIG. 1 such as would be seen along the sight line 22 as applied to FIG. 1; j

FIG. 3 is a side elevational view, partially broken away, of a clutch employed in the apparatus of FIGS. 1 and 2;

FIGS. 4 and 5 are the left and'right end elevational views of the clutch seen in FIG. 3;

FIG. 6 is an enlarged sectional view asseen along the line 66 of FIG. 1;

FIG. 7 is a sectional view taken of FIG. 6;

FIG. 8 is an elevational view, partially broken away, of a block employed in conjunction with the clutch of FIGS. 3-5 and which is also seen in FIG. 7;

along the line 77 FIG. 9 is an elevational view of a plate employed in conjunction with the clutch of the preceding views, with certain of the clutch elements being shown in dotted line;

FIG. 10 is aside elevational view, partially in section,

of a directing valve employed in the apparatus ofFIG. 1; FIG. 11 is a sectional view, taken along the sight line 11-11 of FIG. 10; 7

FIG. 12 is an elevational view partiallyin section, of a v FIG. 15 is a schematic view'or diagram of the interconnection of the valves of FIGS. 10-14; and FIG. 16 is a schematic view of the actuating system of FIG. 1 with certain valves shown in section.

In the illustration given, and with particular reference to FIGS. 1 and 2, the numeral20 designates generally a base or frame adapted to carry the inventive timer. The timer itself is seen at the upper right-hand'portion of FIG. 1 and is generally designated by the numeral 21, The timer 21 includes a line shaft 22 which is adapted to be driven through a gear train 23by meansof the inventive timer generally designated 24 and which is seen on the left-hand side of FIG. 1. j V

The piping and valving generally designated by the numeral 25 at the lower right-hand portion of FIG. 1 has to do with the previously referred-to one revolution operation, and description of this portion of the invention will occur later in this specification.

The entire timer is intended to be a self-contained unit, as can be appreciated from a consideration of FIG. 2, wherein the base is equipped with a cover, shown in dotted line and designated 26. The cover is apertured in the top to permit-the extension of a control knob 27 employable to commence operation of the timer. The cover or casing 26 is also apertured as at 28 (still referring to FIG. 2) to permit extension of a conduit 29 for coupling to a source of pressure fluid (not shown). Normally, compressed air at shop line pressure of p .s.i. is coupled to the conduit 29.

The output of the timer 24 is in the form of rotation of a spur gear 39 (see FIG. 2) which operates against a main gear 31 which is coupled to the line shaft 22. The gears30 and 31 make up the gear train 23 previously referred to.

The. timer 21 includes a plurality of poppet valves 32- which are actuated by cams 33 at various times according to the dictates of a processing operation, It will be seen that the timer 21 is generally of the typeshown in the above-mentioned Mead. Patent No. 2,946,346, and reference is hereby made to that patent'for additional details of construction and operation not herein given.

The pneumatic motor will now be described, and this can be best appreciated from a consideration of FIGS. 6 and 7.

Pneumatic motor description In FIG. 6, the base 20 is again designated and is seen to support a pair of cylinder and piston rod units 34 and 35. The unit 34 includes a cylindrical casing 36 interiorly equipped with a piston 37 from which extends a'piston rod 38. Pressure fluid is supplied through a fitting 39. 7 V r V In similar fashion, the unit 35 includes a casing 40 having a cylindrical interior 41 in which a piston 42 is slidable, the piston being equipped with a projecting piston rod 43. Fluid for the movement of the piston is provided through a port 44.

The piston rods 38 and 43 operate against a one-way rotary clutch generally designated '45, which is also seen in FIGS. 3-5 and 7. a

Still referring to FIG. 6, it will be seen that the clutch 45 includes a block 46, the block 46 being shown alone in FIG. 8. The block 46 is seen to be bored as at 47 and 48 for the receipt of the piston rods 38 and 43, respectively. In operation, pressurizing the chamber 49 of the cylinder unit 34 results in movement of the piston 37 to the left, causing the block 46 to move accordingly, which necessarily causes the piston rod 43 and its'associated piston 42 also to move to the left- -at this stage thecylinder chamber 41 of the cylinder unit 45 being vented to atmosphere through a piping system to be described hereinafter. The operation of the invention I 45, resulting in slow or l e 3 further contemplates that moved 'to its full left position, compressed air will be supplied to the unit 35, while the unit 34 is vented so.

as to cause a movement of the system just described to the right. Thus, the block 46 is reciprocated over the I throw of the piston rods 38 and.43 which are mounted in coaxial relation. 7

The reciprocating movement of'the block 46 is converted into rotary motion by'the remainder of the'clutch stepwise rotation of the motor shaft 50, r

The motor shaft 59 ismounted in a pair of bearings 51 and 52".(see FIG. 7), with the bearings 51 and 52' heingsupported on the frame 26. The 01111265145 as seen in FIG. 7, is interp'osed between the spaced-apart bearings 51'and 52 and the block 46 is slotted as at 53 to accommodate the extension of the shaft 50 therethrough. r

after the piston 47 has beenwhere the valve includes a pilot body 85 anda main. body 86 suitably securedtogether by means of bolts 86a.

a Foradditional details 'on this valve, "Lieser Patent: No. 2,946,321 may be consulted. i a V g g.

The pilot body portiorrof the valve is equipped with a bore'or' chamber 87in which a, pilot: spool 88 is I slidably mountedj The'function of the pilot spool 88 is .to position arslide valve'89 in either one of two positions The shaft 50, in the intermediatelongitudinal portion extending through the clutch 4 5, is equipped .with a hexagonal sleeve 54 secured thereto by means of a setscrew 55 (seeFIG. 6). Mounted on the sleeve 54 and constituting part of the clutch 45 are a pair of clutch plates 56'and 57 (see FIGS. 7 and 9). Each plate 56 and 57 is equipped withperirnetrically spaced slots as at 58, in whichdiscs 59 are positioned. v r

Providing the means for turning the clutch plates 56' and 57 through the discs 59, are apair of drive plates 60 and, 61. The plate 61 is partially brokenaway in FIG. 6 to show the arrangement of the elements 57 and 59, the discs 59 being urged to a nonclutching position bymeans of springs 62. Stillreferring to FIG. 6, it will vbe seen that. the drive plate61is pivotally mounted on the block 46 bymeans of a stud v63. The stud 63, as;

Well as an identical stud 64 employed in conjunction with the drive plate 60, can be seen in FIG. '3. The: studs 63 and 64 are received within bores 65 and 66, respec- 1 tively (seealso FIG. 8), and are releasably held by means of resilient ring washers :67. The various plates discs,

and blocks are maintained as a compact unit by means of retaining rings-68 (see FIGS. 3-5). In FIG. 7, it

is seen that retaining plates 60a and 60b confine the discs 59 and springsf62 associated with drive plate 60,. while-the retaining plates 61a and 61b perform the same:

function for drive plate 61...,

In the operation of the clutch 45, shifting of th e 'block I 46 one way or the other in FIG. 6 results in an engagement between either the plates 61 and 57, or 60 and 56, as the case may be." For e xample, movement of the block 46 to the right'aswhere the chamber 41 is pressurizedcausesthe plate 61 to pivot on the stud 63 and urges the discs'59 against the plate-57. so as to turnthe shaft50. ment to the right has no effect on .the plate 56, since the drive plate 60 is not effective tourge the discs 59 against the clutch plate 56. However, on the return stroke..as where; the chamber 49 is pressurized-the reverse is true, i.e., the clutch 56 being driven by the drive plate 1 60, which imparts further rotational movement to the shaft 50. As can be appreciated from the arrows. ap

plied to FIGS. and 5, the pivoting movement of the drive'plates 60 and 61 are accumulative, and, in'the illustration given, the strokes are short, so thatapproximately 125 actuations of the two cylinders 34 and 35' are required to cause one revolution of the. shaft 50., r The pivotal movement of the drive plates 60-and61 is a departure from straight-line motion, but because of the shortness of the stroke and the fact thatthe action' takes place at the top and bottom of the arcs, this departure from straight-line motion is unobjectionable. a To. provide the alternate actuation of the cylinder and On the other' hand, this same move-ipiston rod .units 3 4 and 35, the block 46 'is equipped-" with pro ecting pins 69 and 70' mounted in bores 71 and a 72, respectively. The pins 69 and 79 operate against the balls 74 and 75 of poppet valves'76 and 77,-respectively, so as to vent a first airdirecting valve generally designated 78.'

The valve 78 is seen -in FIG. 1 .and is connected by 7 means of flexible conduits 79 and :80 to the. poppet. valves 76 and 77. The poppet valves 76 and 77 are supported on brackets 81 and. 82 (see FIG; 6) which are'mounted 'onthe cylinder units 34 and 35? The air-directing valve'78 is also coupled by means; of 1 flexible; conduits 83 and 84 to the fittings 39 and 44 pro-.

vided as part of the aircylinders 34 and 35. The air-directing valve 78 is seen in FIGS.- l0 and,1l,

so as to cause compressed air to flow outof one or the other of outlet ports or 91r -The air entersthrough aninlet-asat92 (see alsoFIG. 1 andrflows through'an annular recess 93 into the chamber 94. As such it "communicates with an L-shaped passage95 (see FIG. 7 11) 'soas to issue outof theport- 90 when the pilot spool '38 is in the position seen in FIG. 1O. Inlother words,

when the pilot is at the left, compressed'airissuesout of'the left. port.

To move the pilo t spool to the right in FIG. 10, isonly necessary to 'vent. the port 96, which is seento be 1 coupled to the poppet valve 76. The characteristic of the,

valve seenin FIGS.' 10 and 11 isithat the. pilot stays ina given end position until the other end is'vented, botlriendsi being under the 7 same pressure by virtue ofithe longitudinal bore 97.

Operation of pneumatic motor W i Referring now to FIG. '1. the operation of the pneu-v maticrmotor 24 is seen to involve the followingrA' pressure fluid (usually compressed air) is supplied to the directing valve 78 by means of the conduit 98. As soon as this happens, air is vented through the poppet 76 .to: cause '7 thepilot spool-tis to move upwardly (in FIG. 1). and 1 thus supply compressed air through the conduit 83 to'the air cylinder 35. This results in movement of the block downwardly until the pin 70 engages the poppet. 77', initiate another shift of the pilot spool 88, which then vents T the air cylinder- 35 through the port 99 (see FIG, 11)

and pressurizes the. air cylinder 34 through the conduit 84.. L'r the commercialformot the-invention, the. clutch 45 1 1s aPos-O-Grip Clutch manufactured by Machine Accessories,. Inc., of Minneapolis,Min'nesota; and by adjusting the air pressure and exhaust from valve 78, speeds from 1 zero to-SOO r.p.m. at 25 p.s.i. inlet pressure are obtained.

The shaft 50 is coupled through a -10:1 gear reduction tra n as at 23, so that the line fshaft speed may be varied from zero to 30 1'.p.n'1.'

operations differing in time.

revolution.

For thispurpose, the line shaft 22 is equipped with an 7 extra cam as at100 (see FIG. 1), which is arranged to depress a plunger 101- provided as part of an on-olfvalve 5 generally designated 102 and which is seen in FIG. 14.

The valve 102 '(asiseenin FIG; 1) is equipped with a mufiier 103 to reduce the noise; level of the exhaust, the" mufiler being threadedly received within a transversew threaded bore 104 (see FIG. 14). Compressed air from the fitting 29-enters a-TltlS (see FIGS. 1 and 2), and by means of ,flexible conduit 106, entersthe top or cndbore seen in FIG. 14, air entering the bore 107 is precluded by virtue of the position of plunger 101 from flowing through the valve and exiting from the outlet port 108. The outlet port 108 provided on the other end or bottom as seen in FIG. 1, communicates by means of flexible pipe 109 to an interlock bleed valve generally designated 110 and which is also seen in FIG- 13. When the plunger 191 is depressed, compressed air flows through the valve 102 to the valve 110 to actuate the latter. This will occur whenever the cam 100 engages the plunger 101, and the valve 110 is arranged to be @responsive to the'steady air pressure from valve 102 but to only momentarily bleed a second air directing valve generally designated 111. The valves 111 and 78 are substantially the same except for the location of the exhausts. In the valve 111, the exhaust i112 is opposite to the inlet 11-13, whilein the valve 73 the exhaust 92'is on the same side as the air inlet port 92. However, the interior of the valves, including the pilot spools and slide valve elements, are thesame.

The valve 111 has within it a spool 88 which is normally: positioned in the upward or dotted line position designated 88 in FIG. 1. Whenthe line shaft 22 is rotating (as pictured in FIG. 1, since the cam 100 is not against the plunger 101), the pilot spool in the valve 111 is in its lower position so as to direct air from the inlet 113 through the line 98 to the directing valve 78.

.At the completion of one revolution, the depression of the plunger 101 by the cam 100 results in a momentary bleed of the port 114 of the directing valve 111 so as to position the spool in theposition designated 88'. This cuts oil flow of compressed air through the directing valve 78 and shuts down the timer. The timer is restarted by depressing the plunger 27 which is provided as part of another on-olf valve seen in FIG. 12. Normally, the valve is in the off position shown, wherein the valve stem 115 engages a seat 116, thereby isolating the inlet port 117 from the outlet port 118. Momentary depression of the handle 27 brings these two ports into communicaiton and vents the port 119 of the valve 11, permitting the pilot spool to move from the 88 position and direct compressed air from the T 105 to thedirecting valve 78. This then initiates another cycle of operation,'i.e., one revolution to shaft 22. i

The interlock bleed valve 110 provides an important function of performing a momentary bleed while being under continuous pressure, it being apparent that the valve 102 is maintained in an open condition by virtue of the continuous depression of theplunger 101. This stems from the fact that the cam 100 comes to a stop in contact with the plunger 101 so that compressed air from theline 106 exerts a continuous pressure on the interior of the valve 110 by means of the inlet port 120.

Referring now to FIG. 13, the numeral 121 designates a tubular body which is equipped with a longitudinallyextending bore 122. The bore is closed at one end as at 123 by means of a plug equipped with a suitable O-ring seal 124, the plug being threadedly received'on the threads 125 provided on the interior of the bore 122.

t The opposite end of the bore provides the port 120, and mounted within the bore is a larger spool 126 adjacent the closed end. The spool 126 itself has an axially-extending bore 127 and an upstanding hollow post 128 extending axially toward the open end equipped with the port 120.

The bore 122 is equipped with a second spool 129 also equipped with a through bore 130. The spool 129, midway of its length, is equipped with an annular, in-

wardly-extending shoulder 131 which provides a seat for a ball check valve 132. The ball 132 is urged against the seat by means of a coil spring 133. The spools 129 and 126 are urged apart by a second and heavier coil spring 134 which is partially received within both spools and which surrounds the hollow post 128.

In operation, two transverse bores are provided, one at 135 which receives a fitting 136 communicating with the flow port 114 ofthe directing valve 111 of FIG. 1. The other transverse bore includes opposite openings 137 spaced toward the closed end 123 from the first bore Between the two. transverse bores 135 and 137, the body 121 provides an annular seal as at 138 operating against the smaller diameter spool 129. V

Inoperation, compressed air flows into the port from the valve 102. This air cannot flow longitudinally through the smaller diameter spool 129 because ofthe closed position of the ball check valve 132. This results in the smaller diameter or innerspool 129 being urged to the right in FIG. 13 into further telescoping relation with the larger spool 126. .Ultimately, this brings the hollow post 128 into engagement with the, ball check valve 132 soas to upset the same, i.e., remove, it from its seated position on the seat 131.; Thereupon, compressed air is able to flow through the bore. 139 of the hollow post 128 and through the constricted bore 140 into the space 141 adjacent the closed end 123 of the valve 110. This serves to move the larger spool 126 to the left, which necessarily returns the inner spool 129 to its original position. During the "reciprocator-y movement of the inner spool 129, the seal developed bythe O-ring 142 and the outersurface of the inner spool 129' is broken so that communication is established between the ports and 137, thereby providing a momentary or short term venting of the'pilotchamber in valve 111.

So long as air pressure is applied to the interior of the valve 110 by virtue of the valve 102 being maintained in open condition, the outer spool 126 is maintained in its left position, i.e., from that shown, and, because of the influence of the compressed, air in the chamber portion 141.

When the handle or plunger 27 is operated to recommence the one-revolution operation, the valve 102 is changed to the condition seen in FIG. 14, wherein the port 108 is connected to the port 104, valve 110 thereby beingexhausted to atmosphere. This removes all pressureifrom the line 109 (see FIG. 1) and from the chamber portion 141, permitting the coiled spring 134 to return the outer spool 126 to the position shown. Any air trapped within the inner spool and to the right of the ball'check valve 132 is vented through the ports 142. The interlocked bleed valve 110 thus is returnedto the FIG. 13 condition so as to be ready for stopping the rotation of'the shaft 22 when the cam 110 completes its travel and once again engages the plunger 101.

While, in the foregoing specification, a detailed description of an embodimentof the invention has been set down for the purpose of explanation, many variations in the detailsherein given may be made by those skilled in the art without departing from the spirit and scope of the invention. g

I claim: V 1. A pneumatic motor adapted to power a pneumatic timer, comprising:

a frame equipped with spaced bearings, a shaft journaled in said bearings and adapted to be coupled to said timer,

a one-way rotary clutch coupled to said shaft between said bearings, said clutch including a block adapted to reciprocate transversely to the axis of said shaft to provide a few degrees of shaft rotation for each reciprocation,

a pair of pneumatic cylinder and piston rod units mounted on said frame in alignment with said block on opposite sides thereof and coupled thereto for reciprocating the same, and

means including a source of pressure fluid and a directing valve for alternately delivering pressure fluid to said pneumatic cylinder and piston rod units for exhausting pressure fluid therefrom, said alternately delivering means including a pair of poppet valves mounted on said frame, one on each side of said block and'engageable sequentially tliereby during recip j' rocation thereof for controlling said directing valve.

ZjThe structure of claim 1 inwhich a plurality of cams areopera'tively connected to said shaft, and valve means 'operatively associated with one of said cams for.

stopping the flovvof pressure fluid to said directing valve after a predetermined arcuate movement of said shaft.

3. The structure of claim 2 in which said valve means includes a second directing valve fordelivering pressure fluid to' the first-mentioneddirecting valve, said second directing valve including a pilot-equipped chamber for "directing the flow of pressurefluid through's'aid second directing valve, a momentary bleedvalve connected to one side of said'chamber and actuated by said one cam to move said pilot in one direction, and meansfor bleed ing pressure fluid from theother'side of said chamber to move said pilot-inthe opposite direction. a a

4. A pneumatic motor adapted to power a pneumatic timer, comprising: t I a frame equipped with spaced bearings, a shaft journaled in said bearings andadapted t'o be'c'oupled ranged for recip iocal movement transverse as said shaft, said units being arranged for piston rod movement transt verse to said 'shaft, with saidtbloc k being'equippe'd with oppositely disposed bores receiving said piston rods, and 1 means including a source of pressure fluid fortalternate-y ly stroking said, piston rods, said stroking means, com,-

prising a directingvalve equipped with a vtwo-position pilot for alternating the valve condition to alternately 1 deliver" pressure fluid to'one-unitwhile exhausting'pressure fluid from the other unit, and a pair of-poppet valves on said frame in juxtaposition with said clutch and 'ac-. t tuated byjsaid clutchto move said pilot from'one poSition'to' the other. and thereby cause said directing valve 7 to alternatelydeliver pressure fluid to said units, said poppet valv'es'being positioned above said'units andjal-.

ternately engage'able' by said "block at the =lirnits of its reciprocatory travel.

to said timer, a one-way rotary clutch coupled to' said shaft between said bearings; said clutch includ ing a block adapted to reciprocate transversely to the axis of said shaft to provide a few degrees; of

shaft rotation for each block reciprocation," Q a pair of pneumatic cylinder and piston rod units mounted on said frame in alignment with and on opposite sides of said block and coupled theretofor reciprocating the same, 7 p

' a source of pressure fluid and a directing valve icon pled to said source, said directing valve being' 7 equipped with a pilot arranged to direct pressure fluid alternately to said unit while exhausting pressure fluid from the unit not receiving pressure fluid,

and a pair of poppet valves said poppet valves being coupled to said directing valve for positioning said pilot as a function of the reciprocation of said block.

5. The structure of claim z in which said valvemean includes first and second valves, said firstvalve being engageable by said one cam and'bein g coupled to said source of pressure fluid, said second 'valvebeing coupled to said first valve forreceiving pressure fluid therefrom for stopping the flow of pressure fluid to. said directing valve.

6. In a pneumatic motor, a frame,*a shaft mounted for rotation on said frame, a one-way rotary'clutch coupled to said shaft, a pair of oppositely-acting pneumatic cylinder and piston rod unitsoperatively connected to said clutch for rotating said clutch-a few degrees for each piston rod stroke, said clutch including a block armounted on said frame on 'opj posite sides of saidblock so as to be adjacent to' one of said pneumatic cylinder and piston rod units, j

'7. The structure ofclaim 6 in which said frame "is equipped'with meansfor limiting the operation of said stroking means upon the "completion; of one revolution of "said shaft, saidlimiting means includes valve means} vthe flovv of pressure coupled to said shaft" for stopping fiuid to said stroking meansa g g f 8 In a pneumatic motor; a frame, a shaft mountedfor rotation on said frame',, a plurality of cams .on said shaft,

, a plurality of valvesi on said frame, one for each cam andractuated thereby a one-way rotary clutch coupled to said shaft, .a pair'of oppositely-acting pneumatic cylinder and piston rodunits operatively connected to said clutch for rotating said clutch a few degrees for each "piston J rod stroke, and means including a source of 'regulated pressure'fluid for alternately stroking said piston rods whereby the rotationalspeed pof said'shaft can be varied gradually without change of mechanical parts."

References by the Examiner 3 V UNITED- STATES PATENTS V -Osborne 91--420 -39,3l3 7/3'1 France. v I a Y (Addition to No. 684,896) FREDENGELTHALER, Pra Examiner. SAMUEL' LEVINE, Examiner. 

1. A PNEUMATIC MOTOR ADAPTED TO POWER A PNEUMATIC TIMER, COMPRISING: A FRAME EQUIPPED WITH SPACED BEARIONGS, A SHAFTA JOURNALED IN SAID BEARINGS AND ADAPTED TO BE COUPLED TO SAID TIMER, A ONE-WAY ROTARY CLUTCH COUPLED TO SAID SHAFT BETWEEN SAID BEARINGS, SAID CLUTCH INCLUDING A BLOCK ADAPTED TO RECIPORCATE TRANSVERSELY TO THE AXIS OF SAID SHAFT TO PROVIDE A FEW DEGRESS OF SHAFT ROTATION FOR EACH RECIPROCATION, A PAIR OF PNEUMATIC CYLINDER AND PISTON ROD UNITS MOUNTED ON SAID FRAME IN ALIGNMENT WITH SAID BLOCK ON OPPOSITE SIDES THEREOF AND COUPLED THERETO FOR RECIPROCATING THE SAME, AND MEANS INCLUDING A SOURCE OF PRESSURE FLUID AND A DIRECTING VALVE FOR ALTERNATELY DELIVERY PRESSURE FLUID TO SAID PNEUMATIC CYLINDER AND PISTON ROD UNITS FOR EXHAUSTING PRESSURE FLUID THEREFROM, SAID ALTERNATELY DELIVERING MEANS INCLUDING A PAIR OF POPPEWT VALVES MOUNTED ON SAID FRAME, ONE ON EACH SIDE OF SAID BLOCK AND ENGAGEABLE SEQUENTIALLY THEREBY DURING RECIPROCATION THEREOF FOR CONTROLLING SAID DIRECTING VALVE. 